Chantal's not a hoarder; she has no emotional attachment to any of that stuff, and would feel no shame or anxiety if somebody were to haul it all out tomorrow.
She's just a fucking slob, full stop, complicated by the fact that she's too debilitated by her obesity and its related ailments to do even the most basic housekeeping, much less catch up on months of neglect. Even if she wanted to clean house at this point, she cannot physically do it; that's just a simple fact.
So as disgusting as Chantal is, I'm assigning most of the blame for the squalor they live in to James. He's an able-bodied adult, and there is no reason he can't break down Chantal's boxes and haul them out to the recycling dumpster. He should have been doing that all along, once he realized Chantal not only wasn't going to do it, but that she is actually incapable of doing so.
That he's lived in that apartment for nine months and allowed a mountain of boxes to stack up in the kitchen like that is inexcusable. Seriously, it just fucking is.
Maybe he thinks, "Well, they're Chantal's boxes; why should I have to deal with them?" Maybe he thinks, "If I just keep stacking them here, maybe Chantal will get so disgusted, she'll finally deal with them." Maybe he's so resentful of Chantal's consoomerism, he's engaged in a stubborn, childish refusal to deal with the consequences of it.
But there is also no reason he can't fucking run a vacuum, or mop the kitchen floor, because even if the boxes are Chantal's, he's still responsible for those tasks--or should be. And, as we've seen, he doesn't. Apparently, he's such a fucking sperg that he needs a mommy (or mommy substitute) to do all the housekeeping for him; without one on hand, everything just goes to shit, and he's too much of a sperg to even recognize there's a problem, much less identify what to do about it.
I've never seen him sticking around to care for Chantal once she's bedbound; he can't even cook for himself, doesn't clean, has a preschoolers' level of self-absorption, and, as the months have dragged by, has obviously realized that the Chantal he used to live with was a far cry from what she has since become. Their lease expires in April, and I fully expect him to move back to his mother's place. He'll lose his half of the deposit, as he fucking well should, but since he'll never move out of his childhood bedroom again it hardly matters.